examples: fix error handling in auth example

examples/auth/index.js

@@ -59,14 +59,14 @@ function authenticate(name, pass, fn) {
   if (!module.parent) console.log('authenticating %s:%s', name, pass);
   var user = users[name];
   // query the db for the given username
-  if (!user) return fn(new Error('cannot find user'));
+  if (!user) return fn(null, null)
   // apply the same algorithm to the POSTed password, applying
   // the hash against the pass / salt, if there is a match we
   // found the user
   hash({ password: pass, salt: user.salt }, function (err, pass, salt, hash) {
     if (err) return fn(err);
     if (hash === user.hash) return fn(null, user)
-    fn(new Error('invalid password'));
+    fn(null, null)
   });
 }
 
@@ -99,8 +99,9 @@ app.get('/login', function(req, res){
   res.render('login');
 });
 
-app.post('/login', function(req, res){
+app.post('/login', function (req, res, next) {
   authenticate(req.body.username, req.body.password, function(err, user){
+    if (err) return next(err)
     if (user) {
       // Regenerate session when signing in
       // to prevent fixation

test/acceptance/auth.js

@@ -22,7 +22,7 @@ describe('auth', function(){
       .expect(200, /<form/, done)
     })
 
-    it('should display login error', function(done){
+    it('should display login error for bad user', function (done) {
       request(app)
       .post('/login')
       .type('urlencoded')
@@ -36,6 +36,21 @@ describe('auth', function(){
         .expect(200, /Authentication failed/, done)
       })
     })
+
+    it('should display login error for bad password', function (done) {
+      request(app)
+        .post('/login')
+        .type('urlencoded')
+        .send('username=tj&password=nogood')
+        .expect('Location', '/login')
+        .expect(302, function (err, res) {
+          if (err) return done(err)
+          request(app)
+            .get('/login')
+            .set('Cookie', getCookie(res))
+            .expect(200, /Authentication failed/, done)
+        })
+    })
   })
 
   describe('GET /logout',function(){